MCF-7 Cell Death Research Articles

Intracellularly transported adenosine induces MCF-7 human breast cancer cells by accumulating AMID in the nucleus

Extracellular adenosine induced apoptosis of MCF-7 human breast cancer cells in a concentration (10μM–10mM)- and treatment time (24–72h)-dependent manner, and the effect was inhibited by the adenosine transporter inhibitor dipyridamole, but not an inhibitor of adenosine kinase, an inhibitor of AMP-activated protein kinase, or inhibitors for A1, A2a, A2b, and A3 adenosine receptors. No significant activation of caspase-7, -8, or -9 was obtained with adenosine. Adenosine promoted translocation of apoptosis-inducing factor (AIF)-homologous mitochondrion-associated inducer of death (AMID) from the cytosol into the nucleus, although the total amount of AMID was not affected. Adenosine-induced MCF-7 cell death was abrogated by knocking-down AMID. The results of the present study indicate that intracellularly transported adenosine induces MCF-7 cell apoptosis by accumulating AMID in the nucleus in a caspase-independent manner.

Investigating the efficiency of novel metallo-phthalocyanine PDT-induced cell death in MCF-7 breast cancer cells

Cancer cells possess an innate resistance to inducers of the death program. Novel phthalocyanines with improved physiochemical properties harbor the potential for use in photodynamic therapy (PDT); a rising treatment alternative preferred for its mostly asymptomatic application and unique mechanism of action. This study aimed to determine whether in vitro PDT with two new metallo-phthalocyanines (metallo-Pcs), AlPcSmix and GePcSmix, are similarly effective in overcoming resistance to cell death in MCF-7 cells with a brief comparison to an established chemotherapeutic agent, etoposide. Optimum induction of cell death in these cancer cells was initially determined via measurement of cellular respiration and energy production levels. Indications of cytotoxicity and cell stress were evaluated and resultant levels compared to those in cells treated with etoposide. Initial findings report AlPcSmix is predominantly more detrimental to cellular function and homeostasis when excited via red light irradiation of 15 J/cm(2). It appears GePcSmix requires higher dosage administrations to achieve similar responses within identical populations. However, due to the mechanism of PDT application, our findings indicate a greater toxic effect with both phthalocyanines when compared to etoposide of higher dosage within MCF-7 cells. Both phthalocyanines, despite similarity in structure, indicate induction of different cell death response pathways based on their toxicity potential. These therefore show great promise as potential PDT agents for the treatment of cancer.

Differential signaling involved in Sutherlandia frutescens-induced cell death in MCF-7 and MCF-12A cells

Ethnopharmacological relevanceThe scientific study of natural products traditionally used in anticancer preparations has yielded several therapeutically relevant compounds. One of these traditional preparations with potentially beneficial properties is aqueous extracts of Sutherlandia frutescens, a shrub indigenous to the Western Cape region of South Africa. The aims of this study were to evaluate in vitro efficacy of these preparations on the MCF-7 breast adenocarcinoma and MCF-12A non-tumorigenic cell lines in terms of cell proliferation, cell morphology and possible induction of cell death. Materials and methodsCrystal violet staining was used to evaluate cell proliferation, light-and fluorescence microscopy were used to investigate both intracellular and extracellular morphological features of apoptosis and autophagy (e.g. membrane blebbing, condensed chromatin and intracellular lysosomes), while flow cytometry quantified cell cycle changes and induction of apoptosis through analysis of the flip-flop translocation of phosphatidylserine. ResultsCrystal violet staining showed a time- and dose specific response to aqueous Sutherlandia frutescens extracts, revealing exposure to 1mg/ml aqueous extract for 48h to be ideal for comparing the differential effects of Sutherlandia frutescens in the MCF-7 and MCF-12A cell lines. Microscopy showed distinct morphological changes with hallmarks of apoptosis being observed in both cell lines. Flow cytometry revealed a decrease in actively cycling cells in both cell lines, and a 4.36% increase in phosphatidylserine translocation in the MCF-7 cell line, indicative of apoptosis induction, while fluorescence microscopy showed evidence of the induction of autophagy. ConclusionsAnalyses revealed the carcinogenic MCF-7 cell line to be more susceptible to the cytostatic and cytotoxic effects of aqueous extracts of Sutherlandia frutescens when compared to the non-tumorigenic MCF-12A cell line, thus warranting further research into the exact cellular mechanisms involved and the possible synergistic activities of Sutherlandia frutescens ingredients.

Induction of Apoptosis in Human Breast Adenocarcinoma Cells MCF-7 by Monapurpyridine A, a New Azaphilone Derivative from Monascus purpureus NTU 568

A new azaphilonidal derivative, monapurpyridine A (MPA), has recently been isolated from the fermented products of Monascus purpureus NTU 568. The structure of MPA was elucidated by nuclear magnetic resonance (1H-NMR, 13C-NMR, COSY, HMQC, and HMBC) and other spectroscopic analyses. Biological evaluation revealed that MPA could induce cell death in human breast adenocarcinoma cells MCF-7, and it has no significant toxicity to normal mammary epithelial cells M10. The MTT assay and flow cytometric analysis were employed to investigate cell viability and cell cycle influenced by MPA. Moreover, we used Western blot and caspase activity assay to demonstrate the activation of caspase-3, -8 and -9 resulted from MPA. All evidence supported that MPA was suitable for developing into a chemotherapeutic or chemopreventive agent against breast cancer.

The scaffold protein MEK Partner 1 is required for the survival of estrogen receptor positive breast cancer cells

MEK Partner 1 (MP1 or MAPKSP1) is a scaffold protein that has been reported to function in multiple signaling pathways, including the ERK, PAK and mTORC pathways. Several of these pathways influence the biology of breast cancer, but MP1’s functional significance in breast cancer cells has not been investigated. In this report, we demonstrate a requirement for MP1 expression in estrogen receptor (ER) positive breast cancer cells. MP1 is widely expressed in both ER-positive and negative breast cancer cell lines, and in non-tumorigenic mammary epithelial cell lines. However, inhibition of its expression using siRNA duplexes resulted in detachment and apoptosis of several ER-positive breast cancer cell lines, but not ER-negative breast cancer cells or non-tumorigenic mammary epithelial cells. Inhibition of MP1 expression in ER-positive MCF-7 cells did not affect ERK activity, but resulted in reduced Akt1 activity and reduced ER expression and activity. Inhibition of ER expression did not result in cell death, suggesting that decreased ER expression is not the cause of cell death. In contrast, pharmacological inhibition of PI3K signaling did induce cell death in MCF-7 cells, and expression of a constitutively active form of Akt1 partially rescued the cell death observed when the MP1 gene was silenced in these cells. Together, these results suggest that MP1 is required for pro-survival signaling from the PI3K/Akt pathway in ER-positive breast cancer cells.

Analysis of biochemical markers of MCF-7 cell apoptosis induced by a recombinant analogue of lactaptin

Earlier we isolated and characterized human milk pro-apoptotic peptide - lactaptin and generated its engineered analog - RL2. It was shown that both lactaptin and RL2 are capable to induce apoptotic death of MCF-7 cells. In this report we have analyzed biochemical markers of RL2 induced MCF-7 apoptosis. The activation of initiator and effector caspases as well as mitochondrial membrane potential and cytoplasm membrane changes were analyzed using flow cytometry and Western-blot methods. We have found that RL2 induced apoptotic death of MCF-7 cells was accompanied by PS exposure on the plasma membrane surface. It also was shown that RL2 has induced dissipation of mitochondrial membrane potential and resulted in activation of initiator caspases 8, 9 and effector caspase 7.

Dimethoxycurcumin-induced cell death in human breast carcinoma MCF7 cells: evidence for pro-oxidant activity, mitochondrial dysfunction, and apoptosis

The factors responsible for the induction of cell death by dimethoxycurcumin (Dimc), a synthetic analog of curcumin, were assessed in human breast carcinoma MCF7 cells. Initial cytotoxic studies with both curcumin and Dimc using MTT assay indicated their comparable effects. Further, the mechanism of action was explored in terms of oxidative stress, mitochondrial dysfunction, and modulation in the expression of proteins involved in cell cycle regulation and apoptosis. Dimc (5-50 μM) caused generation of reactive oxygen species, reduction in glutathione level, and induction of DNA damage. The mitochondrial dysfunction induced by Dimc was evidenced by the reduction in mitochondrial membrane potential and decrease in cellular energy status (ATP/ADP) monitored by HPLC analysis. The observed decrease in ATP was also supported by the significant suppression of different (α, β, γ, and ε) subunits of ATP synthase. The cytotoxic effect of Dimc was further characterized in terms of induction of S-phase cell cycle arrest and apoptosis, and their relative contribution was found to vary with the treatment concentration of Dimc. The S-phase arrest and apoptosis could also be correlated with the changes in the expressions of cell cycle proteins like p53, p21, CDK4, and cyclin-D1 and apoptotic markers like Bax and Bcl-2. Overall, the results demonstrated that Dimc induced cell death in MCF7 cells through S-phase arrest and apoptosis.

Induction of apoptosis and non-apoptosis in human breast cancer cell line (MCF-7) by cisplatin and caffeine.

Molecular targeted therapy by different cell death inducers are recently considered in cancer therapy. The aim of this study was to compare the effect of cisplatin and inositol trisphosphate kinase inhibitor (caffeine) on human breast cancer cell line (MCF-7). The pattern of cell death in MCF-7 cells following the exposure to cisplatin and caffeine in individual and combination forms was characterized. MCF-7 cells at late exponential phase were divided into two groups: control and experimental groups. Experimental group was exposed to cisplatin, caffeine and combination of them and control group was treated by vehicle. Forty-eight hours after incubation, floating and attached cells were collected separately. Flow cytometry analysis and electron microscopy were carried out on both attached and floating cells. Two types of apoptotic and non-apoptotic cells were observed in the floating cells as well as in sub G1 cells of both experimental and control groups by electron microscopy. Both early and late stages of apoptosis were characterized and the attached cells remained unaffected. Although two different forms of cell death (apoptosis and non-apoptosis) were appeared in MCF-7 following exposure to cisplatin and caffeine, apoptosis was the major mechanism of cell death. The combination form of anti-cancer drugs with different mechanisms could decrease the dosage of employed anti-cancer drugs.

Mitoxantrone as a prospective photosensitizer for photodynamic therapy of breast cancer

Photodynamic therapy has the potential to become an effective alternate to surgery for the treatment of cancer. In recent years, there has been a focus on identifying more effective and less toxic photosentisizers for use in photodynamic therapy. The purpose of this study was to assess the effectiveness of mitoxantrone, a chemotherapeutic agent, as a photosensitizer for photodynamic therapy in the MCF-7 human breast cancer cell line. Cytotoxicity was evaluated for different concentrations of mitoxantrone, and photosensitivity was assessed using a non-coherent light source. The percentage of the cell survival after 24 h was investigated using the MTT assay. Overall, the results showed that mitoxantrone is a remarkably efficient photosensitizer that could mediate MCF-7 cell death at a low concentration (5 μM) with modest exposure to light. It is surprising to find that a chemotherapeutic agent can be an effective photosensitizer for PDT in vitro.

Phosphorylation of SAV1 by mammalian ste20-like kinase promotes cell death

The mammalian ste20-like kinase (MST) pathway is important in the regulation of apoptosis and cell cycle and emerges as a novel tumor suppressor pathway. MST-induced phosphorylation of Salvador homolog 1 (SAV1), which is a scaffold protein, has not been evaluated in detail. We performed a mass spectrometric analysis of the SAV1 protein that was co-expressed with MST2. Phosphorylation was detected at Thr-26, Ser-27, Ser-36 and Ser-269. Although single or double mutations had little effects, the mutation of all four residues in SAV1 to Ala (SAV1-4A) had inhibitory effects on the MST pathway. MST2-mediated induction of SAV1-4A protein levels, SAV1-4A interaction with MST2 and the self-dimerization of SAV1-4A were weaker compared to those of wild-type SAV1. SAV1-4A inhibited MST2- and K-RasG12V-induced cell death of MCF7 cells. These results suggest that MST-mediated phosphorylation of four residues within SAV1 may be important in the induction of cell death by the MST pathway.

Improvement of cytotoxic and apoptogenic properties of crocin in cancer cell lines by its nanoliposomal form

Objective: Saffron Crocus sativus L. (Iridaceae) is known for anticancer properties. However, limited effort has been made to correlate these effects to the active ingredients of saffron. In the present study, cytotoxic effects of crocin, the major coloring compound in saffron, and its nanoliposomal form for better cellular delivery are investigated.Methods: HeLa and MCF-7 cells were cultured and exposed to crocin (1, 2, and 4 mM) and liposomal crocin (0.5 and 1 mM). The 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was performed to assess cytotoxicity. Apoptotic cells were determined using propidium iodide (PI) staining of DNA fragmentation by flow cytometry.Results: MTT assay revealed a remarkable and concentration-dependent cytotoxic effect of crocin on HeLa and MCF-7 cells in comparison with non-malignant cell line (L929). Crocin liposomal forms (IC50 values after 48 h: 0.61, 0.64, and 1.2 mM) showed enhanced cytotoxic effect compared with the crocin (IC50 after 48 h: 1.603 mM) in HeLa cells. Crocin and its liposomal form induced a sub-G1 peak in flow cytometry histogram of treated cells indicating apoptosis is involved in this toxicity. Liposomal encapsulation enhances apoptogenic effects of crocin on cancerous cells.Conclusion: It might be concluded that crocin and its liposomes could cause cell death in HeLa and MCF-7 cells, in which liposomal encapsulation improved cytotoxic effects. They could be also considered as a promising chemotherapeutic agent in cancer treatment in future.

Cordycepin-induced apoptosis and autophagy in breast cancer cells are independent of the estrogen receptor

Cordycepin (3-deoxyadenosine), found in Cordyceps spp., has been known to have many therapeutic effects including immunomodulatory, anti-inflammatory, antimicrobial, and anti-aging effects. Moreover, anti-tumor and anti-metastatic effects of cordycepin have been reported, but the mechanism causing cancer cell death is poorly characterized. The present study was designed to investigate whether the mechanisms of cordycepin-induced cell death were associated with estrogen receptor in breast cancer cells. Exposure of both MDA-MB-231 and MCF-7 human breast cancer cells to cordycepin resulted in dose-responsive inhibition of cell growth and reduction in cell viability. The cordycepin-induced cell death in MDA-MB-231 cells was associated with several specific features of the mitochondria-mediated apoptotic pathway, which was confirmed by DNA fragmentation, TUNEL, and biochemical assays. Cordycepin also caused a dose-dependent increase in mitochondrial translocation of Bax, triggering cytosolic release of cytochrome c and activation of caspases-9 and -3. Interestingly, MCF-7 cells showed autophagy-associated cell death, as observed by the detection of an autophagosome-specific protein and large membranous vacuole ultrastructure morphology in the cytoplasm. Cordycepin-induced autophagic cell death has applications in treating MCF-7 cells with apoptotic defects, irrespective of the ER response. Although autophagy has a survival function in tumorigenesis of some cancer cells, autophagy may be important for cordycepin-induced MCF-7 cell death. In conclusion, the results of our study demonstrate that cordycepin effectively kills MDA-MB-231 and MCF-7 human breast cancer cell lines in culture. Hence, further studies should be conducted to determine whether cordycepin will be a clinically useful, ER-independent, chemotherapeutic agent for human breast cancer.

Phospholipase A2 activity-dependent and -independent fusogenic activity of Naja nigricollis CMS-9 on zwitterionic and anionic phospholipid vesicles

CMS-9, a phospholipase A2 (PLA2) from Naja nigricollis venom, induced the death of human breast cancer MCF-7 cells accompanied with the formation of cell clumps without clear boundaries between cells. Annexin V-FITC staining indicated that abundant phosphatidylserine appeared on the outer membrane of MCF-7 cell clumps, implying the possibility that CMS-9 may promote membrane fusion via anionic phospholipids. To validate this proposition, fusogenic activity of CMS-9 on vesicles composed of zwitterionic phospholipid alone or a combination of zwitterionic and anionic phospholipids was examined. Although CMS-9-induced fusion of zwitterionic phospholipid vesicles depended on PLA2 activity, CMS-9-induced fusion of vesicles containing anionic phospholipids could occur without the involvement of PLA2 activity. Membrane-damaging activity of CMS-9 was associated with its fusogenicity. Moreover, CMS-9 induced differently membrane leakage and membrane fusion of vesicles with different compositions. Membrane fluidity and binding capability with phospholipid vesicles were not related to the fusogenicity of CMS-9. However, membrane-bound conformation and mode of CMS-9 depended on phospholipid compositions. Collectively, our data suggest that PLA2 activity-dependent and -independent fusogenicity of CMS-9 are closely related to its membrane-bound modes and targeted membrane compositions.

MTHPC-based photodynamic therapy induction of autophagy and apoptosis in cultured cells in relation to mitochondria and endoplasmic reticulum stress

Photodynamic therapy (PDT), an approved anticancer treatment, is reported as a potent inducer of programmed cell death (PCD) by both apoptosis and autophagy. The present study investigated the kinetics of both autophagy and caspase activation in MCF-7 cells submitted to mTHPC-PDT upon condition of treatment promoting ER accumulation of mTHPC. Fluence-dependent immediate cytochrome c (cyt C) release followed by caspase-9 and -7 activation at 1 h post-PDT evidenced a mitochondrial oxidative stress triggered by high light doses leading to >90% of cell death. ER oxidative stress was monitored by the induction of the glucose-related protein chaperone GRP78. From 6 h post-PDT, GRP78 induction was accompanied by the conversion of LC3-I into LC3-II, the hallmark of autophagosome formation. The formation of acid vesicles evidenced by fluorescence microscopy was obvious from 22 h post-PDT. Twenty-four hours post-PDT, cyt C release decreased and caspase-9 cleavage disappeared, while the expression of cleaved caspase-7 remained significant. At the same time, the profiles of GRP78, cleaved caspase-7 and LC3-II expression were similar irrespective of light doses. In contrast to an inhibitor of caspase activation Z-VAD-FMK, the use of autophagy inhibitor, Wortmannin, impaired cytotoxicity along with an increase in caspase-7 activation. These results demonstrate a valuable contribution of autophagy to cell death in mTHPC-photosensitized MCF-7 cells.

Fas/FasL-dependent and -independent activation of caspase-8 in doxorubicin-treated human breast cancer MCF-7 cells: ADAM10 down-regulation activates Fas/FasL signaling pathway

The contribution of Fas-mediated death pathway to doxorubicin-induced death of MCF-7 cells is not unambiguously elucidated. Thus, this study was conducted to explore doxorubicin-induced Fas/FasL signaling pathway activation in MCF-7 cells and doxorubicin-resistant MCF-7 (MCF-7/Dox) cells. Doxorubicin-induced caspase-8 activation was found to be mediated through Akt/ERK inactivation and FasL-independent Fas pathway in MCF-7 cells, while caspase-8 activation in MCF-7/Dox cells depended exclusively on FasL-stimulated Fas pathway. Suppression of caspase-8 activation restored the viability of doxorubicin-treated MCF-7 cells and MCF-7/Dox cells. Contrary to FasL surface expression exclusively detected in MCF-7/Dox cells, intracellular FasL expression was noted with MCF-7 cells. Promotion of FasL translocation to the cell surface by lysophosphatidic acid evoked a FasL-activated Fas death pathway in MCF-7 cells. Doxorubixin-evoked β-TrCP up-regulation promoted Sp1 degradation, which subsequently suppressed ADAM10 expression in MCF-7 and MCF-7/Dox cells. Doxorubicin-induced down-regulation of ADAM10 reduced FasL shedding, leading to Fas pathway activation in MCF-7/Dox cells. Knock-down of ADAM10 induced death in MCF-7/Dox cells, but marginally reduced the viability of MCF-7 cells. Taken together, our data indicate that Akt/ERK-mediated caspase-8 activation and Fas/FasL-mediated caspase-8 activation mostly elucidate doxorubicin-induced death in MCF-7 cells and MCF-7/Dox cells, respectively. These observations suggest a promising therapeutic modality for overcoming doxorubicin-resistant breast cancer by targeting ADAM10 sheddase activity.

HSav1 interacts with HAX1 and attenuates its anti-apoptotic effects in MCF-7 breast cancer cells

It has been reported that Salvador (SAV) is a core component of the Salvador-Warts-Hippo (SWH) pathway that restricts cell number, by functioning as a dual regulator of cell proliferation and apoptosis in Drosophila. However, the function of its human ortholog hSav1 (also called hWW45) in mammalian cells is poorly understood. In this study, we identified hematopoietic cell-specific protein 1 (HS1)-associated protein X-1 (HAX1), a 35-kDa protein localized to cell mitochondria, as a novel binding partner of hSav1 using a yeast two-hybrid screening technique. Our finding was confirmed by immunoprecipitation and glutathione-S-transferase (GST) pull-down assays of both proteins. Using immunofluorescence staining, we showed that HAX1 and hSav1 interact with each other. Analysis of the anti-apoptotic function of HAX1 revealed that the presence of hSav1 attenuated the HAX1 protective effects from hydrogen peroxide (H2O2)-induced cell death in MCF-7 cells, while knockdown of hSav1 by small interfering RNAs (siRNAs) significantly enhanced the anti-apoptotic function of HAX1. Also, using the Oncomine database, we found several studies in which HAX1 levels were significantly up-regulated and hSav1 expression was down-regulated in breast cancer samples compared to normal breast tissue. In summary, we conclude that hSav1 interacts with HAX1 and attenuates its protective role against apoptosis in MCF-7 breast cancer cells.

Abstract 1744: Hsp27 overexpression enhances the chemosensitivity to MCF7 doxorubicin resistance cells

Abstract Multidrug resistance (MDR) is a major obstacle in cancer chemotherapy and its inhibition is an effective way to reverse cancer drug resistance. In the present study we report that over expression of HSP27 down-regulated MDR1 expression in MCF7/Doxorubicin (MCF7/DOX), a human breast MDR cancer cell line. In MCF7/Dox cells, mutant p53 was found to be accumulated, whereas Hsp27 level is completely depleted. Since Hsp27 was shown to enhance Akt phosphorylation and G2/M cell cycle arrest, a common pathway of Dox-induced cell death in MCF7 cells, we hypothesized that over expression of Hsp27 in resistant cell will sensitize for chemotherapy. HSP27 over expression significantly inhibited mutant p53 and MDR1 (P-gp) expression and MDR1 mRNA. The suppression of MDR1 was accompanied by partial recovery of intracellular drug accumulation and increased cytotoxicity of Doxorubicin, indicating that HSP27 reversed the MDR phenotype by inhibiting the drug efflux function of MDR1. Moreover, nuclear factor-KB activity and IKB degradation were inhibited by HSP27 over expression through down regulation of mutant p53. Interestingly, the over expression of HSP27 negatively regulated the cell growth with significant G2/M arrest of cell cycle, and it could up-regulate endogenous p21 in a p53 independent manner leading to enhanced caspase activation to promote intracellular apoptotic signaling for cell death. Taken together, our results suggested that HSP27 is down regulated in MCF7/Dox resistant cells, and when re-expressed, it down regulates MDR1 expression via p53 and NF-KB., which results in growth suppression and higher sensitivity to Doxorubicin. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1744. doi:10.1158/1538-7445.AM2011-1744

Abstract 17: Bcl-2 is a downstream target of ATF5 that mediates ATF5's pro-survival function in a cell type-dependent manner

Abstract The activating transcription factor 5 (ATF5) is a member of the ATF/CREB family of basic zipper (bZIP) proteins. Recent reports showed that ATF5 loss-of-function causes apoptotic cell death in glioblastoma and breast cancer cells but not in non-transformed astrocytes and human breast epithelial cells. The mechanism for ATF5's cell type-dependent survival function is unknown. We report here that the anti-apoptotic factor Bcl-2 is a downstream target that mediates ATF5-promoted cancer-cell survival in C6 glioma cells and MCF-7 breast cancer cells. ATF5 binds to an ATF5-specific regulatory element (ARE) that is downstream of and adjacent to the negative regulatory element (NRE) in the Bcl-2 P2 promoter, stimulating Bcl-2 expression. Highlighting the importance of Bcl-2 in ATF5-dependent cancer-cell survival, expression of Bcl-2 blocks death of C6 and MCF-7 cells induced by d/nATF5 and depletion of Bcl-2 impairs ATF5-promoted cell survival. Moreover, we found that Bcl-2 expression is not regulated by ATF5 in non-transformed rat astrocytes, MEFs, and human breast epithelial cells (HBEC), where knock-down of Bcl-2 but not that of ATF5 evokes cell death. These findings identify Bcl-2 as an essential mediator for ATF5's cancer-specific cell survival function in glioblastoma and breast cancer cells and provide direct evidence that the cell type-specific function of ATF5 derives from the differential regulation of downstream targets by ATF5 in different types of cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 17. doi:10.1158/1538-7445.AM2011-17

Effects of dehydroepiandrosterone on proliferation, migration, and death of breast cancer cells

Cancer invasion and metastasis are the leading causes of mortality in patients with breast cancer. Dehydroepiandrosterone (DHEA) has a protective role against cancer, however, the mechanism by which DHEA has this effect remains poorly understood. The present study was aimed at investigating the actions of DHEA on the proliferation, cell cycle, death and migration of breast cancer cell lines. We used MCF-7 cells (estrogen receptors positive) and MDA-MB-231 and Hs578T cells (estrogen receptors negative) for these studies. Cell proliferation was evaluated by crystal violet staining, cell cycle by flow cytometry, and cell death by the carboxyfluorescein FLICA analysis of caspase activation. Migration was evaluated by transwell cell migration and wound assay. We also determined the expression of ECM-1 protein by western blotting and RT-PCR in real time. DHEA inhibited the proliferation of all breast cancer cell lines. This was associated with an arrest in the G1 phase of the cell cycle and death in MCF-7 cells. There was no alteration in any of the cell cycle phases or death in DHEA treated MDA-MB-231 or Hs578T cells. DHEA also suppressed the migration of all breast cancer cell lines, independently of the presence of estrogen receptors and decreased the expression of ECM-1 protein in Hs578T cells. These results suggest that the mechanism of DHEA actions against breast cancer involves the inhibition of cell proliferation and the suppression of migration, indicating that DHEA could be useful in the treatment of breast cancer.

Photodynamic effects of porphyrin–polyamine conjugates in human breast cancer and keratinocyte cell lines

Porphyrin-polyamine conjugates bearing two ( cis or trans position) or four spermidine or spermine units were synthesized. We studied the photostability, the hydrophilic/lipophilic balance of porphyrin–polyamine derivatives and the production of singlet oxygen. All these compounds possess physicochemical features required for their use in PDT. Then, we investigated the photocytotoxic efficacy of these porphyrin–polyamine derivatives and the cell death pathway implicated. All compounds appear to be more efficient than Photofrin ® to induce HaCat and MCF7 cell death, essentially by apoptosis. Collectively, these data show that porphyrin-polyamine conjugates could be promising phototherapeutic agents.